Let-off mechanism for looms



May 22, 1928.` 1,670,633 -J. NORTHRQP LET-OFF MECHANISM FOR LOOMS FiledNOV. l5, 1923 5 Sheets-Sheet l May'zz, 192s. 1,670,633

J. NORTHROP LETOFF MECHANISM FOR LOOMS Filed N'ov.'16, 192s 5Smets-sheet 2 May 22,1 1928.

J. NoRTHRoP LET'OFF MECHANISM FOR LQOMS Fi1 ed Nov. 16. 1923.

3 Sheets-Shet 43 Patented May 22, '1928.

UNrriznA STATES PATENT OFFICE.

JONAS NORTHBOP, 0F HOPEDALE, MASSACHUSETTS, ASSIGNOB, BY MESNE ASSIGN-MENTS, TO DRAPEB. CORPORATION, OF HOPEDAIILE,` MASSACHUSETTS, A CORPORA-'non or MAINE.

-LET-OFF MEOHANISM FOB LOOKS.

Application led November 18, 1923. Serial No. 675,123.

The present invention relates to let off mechanism for looms. l

The common types Aof looms provide letof mechanisms by which the warpsare let off from the warp beam at a rate governed by the warp tension.The variations in the rate of let-off are ordinarily regulated by themovements of the whip roll over whic the warps pass. In addition it issometimes desirable to provide"ineans for slack- .ening the Warpsexcessively under abnormal operating conditions ofthe loom. For example,the copending application of Northrop, Serial No. 647,151, filed June22, 1923, Patent No. 1,603,708, illustrates an anti-bang b'y which thewhip roll is bodily moved to relieve the tension of the warps in casethe shuttle is not boxed on the forward beat of the lay, therebypreventing a smash. The connections between the whip roll and let-oifmechanism are such that under these conditions the let-off mechanism isoperated to let off an excessive amount of warp threads from the warpbeam, thereby leaving a thin place in the cloth upon resumption ofoperation.

The object of the present invention is to provide a' loom having alet-of`f mechanism which will be rendered inoperative upon ex-` cessivemovements of the whip roll under abnormal coiditions. To this end theinvention consists in the mechanism herein-` whip roll; Fig. 4 is a sideelevation of the` let-ofi' mechanism; Fig. 5 is a top plan view, partlyin section, of the let-off mechanism under normal operating conditionswhen the lay is at back centerpand Fig. 6 is a top plan view of thelet-olf mechanism when ,it i is rendered inoperative.

y The illustrative embodiment of the invention comprises a loom havin aside frame 10, whip roll 12 and warp eam 14. The

whip 'roll is rotatably mounted in brackets 16 secured to the whip rollshaft 18 which is 'ournaled in blocks 20 slidingly received in rackets22. The rock shaft and connected parts are normally retained in rearwardposition springs 2 The let-off mechanism comprises a worin a clockwisedirection as viewed from above.'

The pawl is pressed toward the ratchet by a compression spring 44vtaking between the pawl andthe pawl arm. provided at its extremityopposite from the pawl with an upwardly extended pin 46 received withinthe' slot 48 of the head 50 which is mounted on and reciprocated by arod 52 connected withthe lay sword of p the loom `(not shown). The pawlarm 38 is providedwith a depending lug 54 adapted to be engaged by thefoot 56 of a pawl stop lever 58 which is connected at its upper end withthe wlip roll shaft 18 through adjustable toothed cap members 60 and 62,the

latter forming a part of the lever 58. The lever 58 is normally urgedrearwardly to .hold the whip roll in an elevated position against thetension. of the Warps hy a compression spring 64 encircling a rod 66which 1s connected at one end with the lever 58 and slidingly receivedin a bracket 68 attached to the frame, the 'spring taking between thebracket 68 and a collar 70 on the rod. The let-.olf mechanism thus fardescribed is similar to that disclosed in the atent -to Northrop, No.1,448,081, dated arch 13, 1923, towhich reference may be had for a moredetailed description. Suftice it to say that on the rearward movement ofthe link 50, corresponding to therearvbyf means of heavy compressionfoi'mer being keyed to the rock shaft and the wheel 26 connecting withthe warp bean The pawl arm is l'Ward beat.' of the lay, the pawl arm 38,which the foot of the pawl 'stop lever. This'position of the parts isillustrated .in Fi .Y 5, corresponding to back center position o the ilay. On the forward movement of the link 50, corresponding to theforward beat of the lay, the rear end of .the slot picks up the stud 46and moves the pawl arm so as to rotate the ratchet and let off the warppawl isst'opped, which depends in turn upon the position of the pawlstop lever as deter- .mined by the pressure 'of the warp threads uponthe whip roll.

The illustrated loom is also provided -w1th an anti-bang of the typedisclosed in the co-v pendingv application of Northrop above referredto. The loom ,frog 76, which may be of any usual or preferredconstruction, is

connected by links 78, one onv each side of the loom, with the rockshaft 18.v The frog is Aalso connected by rods 80 with the pawl stoplever 58 at a point 82 below the upper eri-d of the lever. In case theshuttle is absent from both shuttle boxes on the forward beat of thelay, a dagger .84 on the lay is caused to be depressed in the usualmanner to engage the frog and move it forwardly. @wing to the`connections between the frog and the rock shaft 18, the whip lroll ismoved bodily7 forward from the position illustrated thereby making acloth. 1This excessive let-olf' ment with Afterknokoifef Aoenterm orderto gain aece to the shuttle.

' the parte toward Vbacks-"center in Flg. 1 to that shown in Fig. 2,thereby slackening the wa-rps so that the lay onits forward beat ma pushthe shuttle against the fell without amage to the wa, s. Prov1 s1 on isalso made for knocking oillp the loom which occurs ordinarilyatapproximately front center.

It will be seen that upon o eration vof the ant1-bang and consequentorward movement -of the whip roll the pawl sto lever will be movedforwardl aconsiderable dis! tance, thereby taking the pawl arm out ofthe positive control of the pawl stop. foot 56.

If no additional'means were provided an excessive "amount of warp wouldbe-letolf, thin-place -in the finished \may occur either; on the beat upofthe lay p Y' knockm ofil orupon resumptionof operas' tion.'1 the pawlstp lever is moved out of engageby -the rear end"of fsl'ot"48, the pawlto follow' the `r .of teeth until the pawlengaged-b -the link 50.

sitionthelink'o'moves Y clockwise'rotationlofthepaw e former conditionmay ioccurrif p lever 58y has substantially rearward movement before thepawl returned tonormal the 100m,t e operator or'- @mathe loom over byhand toback-Y and will engage the lug 54 before the-.parts havecompleted their rearward movement, so that upon continued rearwardmovement of the lever the ratchet is rotated to let off an excess ofwarp threads. f

According to the present invention, there is provided a pawl guard orshield 90 of slightly larger diameter than the ratchet wheel and havinga hub 92 loosely rotatable on the shaft 32. The pawl guard normallyrests directly'above the ratchet wheel and asslmes the position shown inFig. 5 out of engagement with the pawl. The guard is' adapted to' bemoved into the position shown in F ig. 6 vto engage an upwardly extendedportion 94 on the pawl to move the latter out of engagementwith theratchet when the anti-hang is caused to operate. To this end the guardis provided with a nose 96 nor-- mally abutting a part of the loomframe, as 'shown in Fig. 5". A bell crank lever 100,

pivoted on thev loom frame at 102, is pro- `which normally -liesimmediately adjacent thefnose 9,6 of the awl guard. It will be seen thatwhen the rogA is moved forwardly, with'consequent forward motion of thewhip roll shaft 18, the cam surface 104 is depressed, thereby rockingthe bell crank about itsl pivot and causing the pawl ard to rotate onequarter revolution to lift the-pawl out of engagement with the ratchet.The extent ofv movement of the ard is determined by the engagement o lsecond nose 110 on the guard with a block 112 on the bracket 33. The lsition shown in Fig. 6. It will be seen t at 106 arts now assume the o'if the loom is now turned over to move the lay to back center the pawlwill play over lnoved'into its final rearward position the 'cam surface104 is raised`,vthereby .permitting the lever 100 to m`ove to its normalposition,

- the lug 108 strikinglthe nose 110 of the guard `and rotates the latterback to its original position, thus permitting normal operation of e lug5i4 before'tl1ev stud 46 is the loom. It will be seenthat thepawl stopll il completed its ard is y position, sozthat t e pawl is.positivelymeld by the' pawl stop in proper position before it isvratchet teeth.

shown land describedit wilL wmle a is preferred a emproyi are specific'Per@ f v'erstoad permitted to' engage the A A that this constructionandvari-an ment'is'- '4 notessential except "so far-as spec' odin theclaimsand; mayb e 'changed or I between the whip roll without departingfrom the broader features of the invention.

The invention Vis claimed is 1. A loom having, in combination, a warpbeam, a let-eilt' mechanism comprising a ratchet, a pawl, means for`oscillating the pawl, means for rotating the warp beam upon rotation ofvthe ratchet, a whip roll, a pawl stop lever connected with' the Whiproll for determining the extent of oscillation of the pawl, an anti-bangfor bodily moving the whip roll to prevent a smash, 'a paWl guard shieldadapted to hold the pawl out of engagement with the ratchetuponaetuation of thevanti-bang, and a lever operated upon movement of thewhip roll for actuating the pawl guard shield. y

2. A loom having, in combination, a warp beam, a let-off lmechanismconsisting of a ratchet and pawl, and means for oscillating the pawl,connections between the ratchet and the warp beam for rotating thelatter to let off the warps, a whip roll, connections and the let-olimechanism for determining the extent of oscilla.- tion of the pawl, anlanti-bang for moving the whip roll in case the shuttley is absent fromboth boxes on the forward beat of the lay, va pawl guard shield, and alever adapted to be moved by the whip roll'to move 1 having beendescribed, what the paWl guard shield into position to hold beam, a whipth'e pawl out of engagement with the ratchet upon the operation of theanti-bang.

. 3. A loom having, in combination, a Warp roll mounted for rockingmovement toward and from the warp beam and also supported for slidingmovementvtoward the front of the loom, a let-oi mecha` nism, meanscontrolled by the rocking move-` ment of said whip rol-l in response tovariations in the tension of the warp to regulate the action of thelet-0H mechanism, an antibang for sliding the Whip roll toward the frontof the loom to prevent a smash, and means actuated `by said slidingmovement for rendering the let-off mechanism inoperative.

, 4. A loom having, in combination, a warp beam, a whip roll mounted forrocking movement toward and from the warp beam and also vsupported forsliding movement toward the front of the loom, a let-oil mechanism,means controlled by the rocking movement of the whip roll to regulatethe action of the let-oit mechanism, an anti-bang for sliding the whiproll toward the front of the loom to prevent a smash, means actuated bysaid sliding movement for rendering the let-off mechanism inoperative,and means for holding the whip roll so that it will not partake of itsrocking movement as it is moved frontwardly by the anti-bang.

5. A loom having, in combination, a warp beam, a whip roll mounted forrocking movement toward and from the Warp beam, a let-off mechanism, abell-crank lever having a short arm that is connected to the Whip rolland a long arm that extends downwardly adjacent the let-ott mechanismand which is adapted to be shifted by the rocking movement of thebell-crank lever t0 vary the action of the let-0H mechanism, ananti-bang for shifting the Whip roll in a d1- rection to slack o thewarp to prevent a smash, and means operable by the Whip rollindependently of said bell-crank lever for rendering the let-offmechanism inoperative upon actuation of the anti-bang.

6. Aloom having, in combination, a warp beam, a whip roll mounted forrocking movement in response to variations in the' tension of the warpand for sliding movement, a let-01T mechanism, means controlled by, therocking movement of the whip roll in response to variations in thetension of the warp to regulate the action of the letolt' mechanism, ananti-ban for sliding the whip roll in a direction to slack o the warpand revent a smash, and means actuate by said sliding movement forrendering the let-oil' mechanism inoperative.

I. A loom having in combination, a warp' beam, a'y whip roll mounted forrocking movement and also for sliding movement, a let-off mechanism,means controlledb)T one `JONAS NoR'rHnoP.

doo

.of said movements of the whip roll 1n re-

